Matrix implant

ABSTRACT

Implants for the fusion or fixation of two bone segments are described. For example, the implants can be used for the fusion or fixation of the sacroiliac joint. The implants can have a matrix structure, have a rectilinear cross-sectional area, and have a curvature.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/859,005, filed Sep. 18, 2015, now U.S. Patent Application PublicationNo. 2016/0081809, which claims priority to U.S. Provisional PatentApplication No. 62/052,379, filed Sep. 18, 2014, each of which is hereinincorporated by reference in its entirety for all purposes.

INCORPORATION BY REFERENCE

All publications and patent applications mentioned in this specificationare herein incorporated by reference to the same extent as if eachindividual publication or patent application was specifically andindividually indicated to be incorporated by reference.

FIELD

Embodiments of the invention relate generally to bone implants that canbe used to fuse two bone segments together.

BACKGROUND

Many types of hardware are available both for the fixation of bones thatare fractured and for the fixation of bones that are to be fused(arthrodesed).

For example, the human hip girdle (see FIGS. 1 and 2) is made up ofthree large bones joined by three relatively immobile joints. One of thebones is called the sacrum and it lies at the bottom of the lumbarspine, where it connects with the L5 vertebra. The other two bones arecommonly called “hip bones” and are technically referred to as the rightilium and-the left ilium. The sacrum connects with both hip bones at thesacroiliac joint (in shorthand, the SI-Joint).

The SI-Joint functions in the transmission of forces from the spine tothe lower extremities, and vice-versa. The SI-Joint has been describedas a pain generator for up to 22% of lower back pain patients.

To relieve pain generated from the SI-Joint, sacroiliac joint fusion istypically indicated as surgical treatment, e.g., for degenerativesacroiliitis, inflammatory sacroiliitis, iatrogenic instability of thesacroiliac joint, osteitis condensans ilii, or traumatic fracturedislocation of the pelvis. Currently, screws and screws with plates areused for sacro-iliac fusion. At the same time the cartilage has to beremoved from the “synovial joint” portion of the SI-Joint. This requiresa large incision to approach the damaged, subluxed, dislocated,fractured, or degenerated joint. The large incision and removal oftissue can cause significant trauma to the patient, resulting in painand increasing the time to heal after surgery.

In addition, screw type implants tend to be susceptible to rotation andloosening, especially in joints that are subjected to torsional forces,such as the SI-Joint. Excessive movement of the implant afterimplantation may result in the failure of the implant to incorporate andfuse with the bone, which may result in the need to remove and replacethe failed implant.

Consequently, it would be desirable to provide an implant for bonefusion or fixation that resists rotation, can be implanted using aminimally invasive procedure, and/or that can be used to rescue a failedimplant.

SUMMARY OF THE DISCLOSURE

The present invention relates generally to bone implants that can beused to fuse two bone segments together.

In some embodiments, an implant for the fixation or fusion of theSI-Joint is provided. The implant can include an elongate body having alongitudinal axis and a rectilinear cross-sectional profile transverseto the longitudinal axis, the elongate body having a proximal end and adistal end. The elongate body can include a plurality of apex strutsaligned with the longitudinal axis and extending between the proximalend and the distal end of the elongate body; a plurality of supportstruts that extend from one apex strut to another apex strut to form amatrix structure; and a first guide pin receptacle located along thelongitudinal axis of the elongate body.

In some embodiments, the rectilinear cross-sectional profile istriangular.

In some embodiments, the rectilinear cross-sectional profile isrectangular or square.

In some embodiments, the elongate body is curved along the longitudinalaxis from the proximal end to the distal end of the elongate body. Insome embodiments, the elongate body has a curvature between about 5 and45 degrees.

In some embodiments, the elongate body has a curvature between about 15and 30 degrees.

In some embodiments, the guide pin receptacle has a circular openingadapted to securely receive a guide pin.

In some embodiments, the elongate body is coated with a titanium plasmaspray.

In some embodiments, the elongate body is coated with hydroxyapatite.

In some embodiments, the elongate body is made of metal.

In some embodiments, the metal is titanium.

In some embodiments, the metal comprises a lattice structure.

In some embodiments, the lattice structure is cubic.

In some embodiments, the lattice structure is hexagonal.

In some embodiments, the lattice structure comprises a plurality ofbeams with a diameter between about 100 to 1000 microns.

In some embodiments, the elongate body is made of a ceramic material.

In some embodiments, the elongate body is mode of a plastic material.

In some embodiments, the elongate body has a porous outer surface.

In some embodiments, all struts are covered in a porous surface.

In some embodiments, all struts are preferentially covered in a poroussurface.

In some embodiments, the porous outer surface has a pore size betweenabout 100 to 1000 microns.

In some embodiments, the thickness of the apex struts and the supportstruts is between about 1 to 5 mm.

In some embodiments, the first guide pin receptacle is located at thedistal end of the elongate body.

In some embodiments, the first guide pin receptacle is located at theproximal end of the elongate body.

In some embodiments, the first guide pin receptacle is located at thedistal end of the elongate body and a second guide pin receptacle islocated at the proximal end of the body.

In some embodiments, the implant can further include a continuouscannula extending between the first guide pin receptacle and the secondguide pin receptacle.

In some embodiments, a third guide pin receptacle is located between thefirst guide pin receptacle and the second guide pin receptacle.

In some embodiments, a plurality of pin receptacles are located betweenthe first guide pin receptacle and the second guide pin receptacle.

In some embodiments, a modular implant for the fixation or fusion of theSI-Joint is provided. The modular implant includes a distal portioncomprising a frame, the frame joined to a distal guide pin receptacleand to a plurality of transverse support struts arranged in arectilinear configuration; a proximal portion comprising a frame joinedto a proximal guide pin receptacle and to a plurality of transversesupport struts arranged in a rectilinear configuration; and at least onerepeating internal portion. The at least one repeating internal portioncomprises a plurality of apex struts joined together by oblique supportstruts arranged in an oblique configuration between the apex struts, aplurality of transverse support struts arranged perpendicularly to theapex struts, the plurality of transverse support struts arranged in arectilinear configuration at both a proximal end and a distal end of therepeating internal portion, and an internal guide pin receptacle securedto the support struts and aligned with both the distal guide pinreceptacle and the proximal guide pin receptacle; wherein the at leastone internal repeating portion is positioned between the distal portionand the proximal portion such that the transverse support struts of thedistal portion are aligned with a first set of transverse support strutsof the repeating internal portion and the transverse support struts ofthe proximal portion are aligned with the a second set of transversesupport struts of the repeating internal portion.

In some embodiments, the oblique supports struts are arranged in an “X”configuration. In some embodiments, the oblique supports struts arearranged in a non-overlapping diagonal configuration.

In some embodiments, the apex and support struts are arranged and spacedto accept bone graft material from the outer surface toward the centerof the implant.

In some embodiments, the graft material is autograft.

In some embodiments, the graft material is allograft.

In some embodiments, the graft material is bone morphogenetic protein.

In some embodiments, the implant does not have any struts that extendfrom the outer surface toward the center of the implant, thereby forminga cavity for receiving a graft material and/or guide pin.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of the invention are set forth with particularity inthe claims that follow. A better understanding of the features andadvantages of the present invention will be obtained by reference to thefollowing detailed description that sets forth illustrative embodiments,in which the principles of the invention are utilized, and theaccompanying drawings of which:

FIGS. 1 and 2 are, respectively, anterior and posterior anatomic viewsof the human hip girdle comprising the sacrum and the hip bones (theright ilium, and the left ilium), the sacrum being connected with bothhip bones at the sacroiliac joint (in shorthand, the SI-Joint).

FIGS. 3 and 4 are embodiments of various straight implants that can beused for the fusion or fixation of a joint or two bone segments.

FIG. 5 illustrates an axial section view of the SI-Joint with an implantfor the fixation of the SI-Joint using a lateral approach that goeslaterally through the ilium, the SI-Joint, and into the sacrum S1.

FIG. 6 illustrates an axial section view of the SI-Joint with an implantfor the fixation of the SI-Joint using a postero-lateral approachentering from the posterior iliac spine of the ilium, angling throughthe SI-Joint, and terminating in the sacral alae.

FIGS. 7A-7C illustrate various embodiments of implants having a matrixstructure formed from a plurality of struts.

FIGS. 7D-7F illustrate various embodiments of implants having a matrixstructure with a plurality of pin receptacles.

FIGS. 7G-7I illustrate another embodiment of an implant having a matrixstructure from various angles and cross-sections.

FIG. 8 illustrates an embodiment of a fenestrated implant.

FIGS. 9A-9D illustrate various cross-sectional profiles of the implantmicrostructure, which can be formed with beam microstructures of varyinggeometries.

FIGS. 10A-10C illustrate various alternative beam microstructures.

FIGS. 11A-11D illustrate various sizes for the beams that form theimplant microstructure.

FIG. 12 illustrates an embodiment of a curved matrix implant.

FIG. 13 illustrates an embodiment of a modular matrix implant.

DETAILED DESCRIPTION

FIG. 3 and FIG. 4 illustrate straight implants 10 with a solid elongatebody 12 that can be used for the fixation or fusion of two bonesegments. The implant 10 shown in FIG. 3 is cylindrical and canoptionally have screw threads along the exterior of the implant body. Asmentioned above, cylindrical screw type implants can suffer fromexcessive rotation. One solution to this problem is the implant 10 inFIG. 4, which has a non-cylindrical cross-sectional area. For example,as shown, the implant 10 can have a triangular cross-sectional area,although other rectilinear cross-sectional profiles may be used as well,including rectangular, hexagonal and the like. Non-cylindrical implantsneed not have a strict rectilinear cross-sectional profile in order toresist rotation. A cross-sectional area that is non-circular willgenerally suffice. For example, a tear drop shaped cross-sectional area,or a cross-sectional area with at least one apex, can resist rotation.Other non-circular cross-sectional geometries that may not have arectilinear component can also work, such as oval cross-sections.

FIG. 5 illustrates insertion of the implant 10 of FIG. 3 or FIG. 4across the SI-Joint using a lateral approach that goes laterally throughthe ilium, across the SI-Joint, and into the sacrum. FIG. 6 illustratesinsertion of the same implant across the SI-Joint using apostero-lateral approach entering from the posterior iliac spine of theilium, angling through the SI-Joint, and terminating in the sacral alae.Many of the implants described herein can be inserted across theSI-Joint in a similar manner.

Matrix Implant

In some embodiments, it may be desirable to provide an implant with anopen frame structure that can be packed with bone graft material and/ora biologic aid, while providing enough strength to facilitate the fusionof a joint or two bone segments without implant bending or failure.

One way to provide an open frame structure is to construct the elongatebody 12 of the implant 10 using a matrix structure, as illustrated inFIGS. 7A-7C and 7G-7I. In some embodiments, each face or side of theelongate body 12 can be constructed using a matrix structure. Theimplant 10 can have a rectilinear overall cross-sectional profiletransverse to a longitudinal axis that extends through the length of theelongate body 12. Each corner or apex of elongate body 12 can be formedwith an apex strut 14 that extends between the proximal end 16 and thedistal end 18 of the elongate body 12. An implant with a triangularoverall cross-sectional profile has three apex struts, while an implantwith a square or rectangular overall cross-sectional profile has fourapex struts, and so on. To form the faces of the implant, support struts20 can be arranged in various matrix structures.

For example, FIG. 7A illustrates one embodiment of a matrix structurewhere the support struts 20 extend diagonally between two apex struts 14and cross each other in an “X” configuration such that the supportstruts 20 define triangular and square openings. Additional transversesupport struts that extend between two apex struts at a right angle toboth apex struts can also be added. The transverse support struts can bepositioned between the “X” support struts and/or can be positioned tocross the middle or intersection of the “X” support struts.

FIG. 7B illustrates another embodiment of a matrix structure where thesupport struts 20 are arranged in an alternating diagonal and transversepattern. In this embodiment, the diagonal support struts on one face ofthe implant are all angled in the same direction such that the diagonalsupport struts are parallel to each other. The support struts 20 definetriangular openings.

FIG. 7C illustrates yet another embodiment of a matrix structure wherethe support struts 20 are arranged in an alternating diagonal andtransverse pattern. In this embodiment, the diagonal support struts areangled in an alternating pattern such that the diagonal support strutsare oriented about 90 degrees to one another to form a zigzag pattern.The support struts 20 also define triangular openings.

The various matrix structures can provide different levels of resistanceto various forces that the implant will be subjected to, includingcompressive, tensile, shear, bending, and torsional forces.

FIG. 8 illustrates an alternative to using a matrix structure to provideopenings. The implant 10 can have an elongate body 12 with fenestrations22. The fenestrations 22 can be circular as shown, and can be ofdifferent sizes in, for example, an alternating pattern of large andsmall fenestrations. The fenestrations 22 can alternatively berectilinear in shape, such as triangular, square, rectangular, and thelike, or curvilinear, such as elliptical, oval, or circular.

In some embodiments, the fenestrations 22 can be triangular, square,rectangular or combinations of the above and can be arranged to form amatrix structure. In other words, the openings in FIGS. 7A-7B defined bythe support struts 20 can be considered fenestrations 22.

The walls of elongate body 12 can be planar and, as described above, canbe formed from support struts 20 and/or fenestrations 22, as shown inFIGS. 7G-7I, for example. Using planar walls to form the elongate body12 can result in a hollow cavity with the same or similarcross-sectional profile as the overall implant. For example, an implantwith a triangular overall cross-sectional profile can also have a cavitywith a triangular cross-sectional profile. The thickness of the wallsand the apex struts and support struts can be between about 1 mm and 5mm, or between about 1 and 3 mm. In addition, the distal ends of thewalls can be tapered.

To facilitate the use of a traditional guide pin with these implants,the distal end of the implant can include a distal guide pin receptacle24 with an opening 26 that is sized and shaped to receive a guide pin,as shown in FIGS. 7A-8. For example, the opening 26 can be circular toreceive a typical guide pin. In some embodiments, the proximal end canadditionally or alternatively have a proximal guide pin receptacle withan opening sized and shaped to receive a guide pin. In some embodiments,a continuous cannula can extend from the proximal guide pin receptacleto the distal guide pin receptacle. In some embodiments, multipleindividual and co-linear guide pin receptacles can be present within theimplant body between the proximal guide pin receptacle and the distalguide pin receptacle.

For example, FIG. 7D illustrates another embodiment of a matrixstructure, similar to the embodiment shown in FIG. 7A, with supportstruts 20 that extend diagonally between apex struts 14 in an “X”configuration. However, in this embodiment, the implant 10 has aproximal guide pin receptacle 28 located at the proximal end of theimplant, a distal guide pin receptacle 24 located at the distal end ofthe implant, and a plurality of internal guide pin receptacles 30 alsolocated along the longitudinal axis of the implant. The internal guidepin receptacles 30 can be attached to the support struts 20 and/or apexstruts 14. As shown, the internal guide pin receptacles 30 are attachedat the intersection points of the “X” shaped support struts 20. Inaddition to receiving the guide pin, the internal guide pin receptacles30 can provide additional support and bracing to the matrix structure.

FIG. 7E illustrates another embodiment of a matrix structure that issimilar to the embodiment shown in FIG. 7D. Both embodiments have “X”shaped support struts 20 and a plurality of internal guide pinreceptacles 30. However, this embodiment has additional support struts20 that extend transversely between the apex struts 14 at right angles.The transverse support struts can be positioned between the “X” shapedsupport struts as shown, or can be integrated into the “X” shapedsupport struts. The transverse support struts can provide additionalsupport and bracing to the matrix structure.

FIG. 7F illustrates another embodiment of a matrix structure that issimilar to the embodiment shown in FIG. 7D. However, instead of having aplurality of guide pin receptacles, the implant 10 has a single guidepin receptacle 32 that extends from the proximal end to the distal endof the implant. This guide pin receptacle 32 can be a tube or cannulathat can be attached to the support struts 20. In some embodiments, thetube or cannula can also have a plurality of fenestrations 34. In someembodiments, the fenestrations 34 can be positioned along the openingsof the support struts, which allows the tube to support the supportstruts 20 while fenestrations promote bony ingrowth and allow theintroduction of bone graft material through the implant.

FIGS. 7G-7I illustrates another embodiment of a matrix structure that issimilar to the embodiment shown in FIG. 7E. This embodiment also has “X”shaped support struts 20 and additional support struts 20 that extendtransversely between the apex struts 14 at right angles. One differencebetween this embodiment and the embodiment illustrated in FIG. 7E isthat the support struts 20 and apex struts 14 in this embodiment havegenerally rectilinear cross-sectional profiles while the embodimentdisclosed in FIG. 7E has generally circular support struts 20 and apexstruts 14. In some embodiments, the apex struts 14 can be chamfered toremove sharp edges and the apices of the implant. In addition, thisembodiment can have a distal guide pin receptacle 24 and a proximalguide pin receptacle, but unlike some of the embodiments describedabove, can lack internal guide pin receptacles. The guide pin caninstead be supported internally by the inherent cross-sectional geometryof the apex struts and/or support struts. Any of the embodiments hereincan have rectilinear, circular, or a combination of the twocross-sectional profiles. The use of the rectilinear struts may allowfor the fabrication of the matrix implant by laser cutting a walledstructure, while tubular struts may be welded together. A laser cutstructure may be structurally stronger than a welded structure, which isimportant for supporting the large loads applied to the implant afterimplantation. The distal end 18 of the implant 10 can also have one ormore openings 29 that allow graft material to be injected distallythrough the implant after implantation. In addition, any of theembodiments described herein can optionally have the internal guide pinreceptacles, or omit the internal guide pin receptacles. FIG. 7Hillustrates a cross-sectional view taken through the transverse struts,while FIG. 7I illustrates a cross-sectional view taken through the “X”shaped support struts.

The implant, including the apex struts and/or support struts of thematrix as well as the beams that form the microstructure, can have avariety of shapes. For example, the beams and/or struts can have across-section that is rectilinear, curvilinear, or combinations of thetwo, as illustrated in FIGS. 9A-9D. For example, the beams and/or strutscan have a circular cross-section as shown in FIG. 9A, or a curvilinearcross-section as shown in FIGS. 9B and 9C, or a square or rectangularcross section as shown in FIG. 9D. It should be understood that thecorners and edges of the beams and/or struts can be rounded off ifdesired.

The implant can be made of a variety of materials. For example, theimplant can be made of a metal or metal alloy, such as titanium orsteel, or a nonmetallic material such as ceramic or polymer. In someembodiments, the implant material can have a certain latticemicrostructure formed from the beam microparticles. For example, thelattice microstructure of the apex strut, support struts and other partsof the implant can result in a rough or smooth surface texture,depending on the surface finishing techniques used, such as polishing orapplication of a metal plasma spray, and the size and shape of the beamsthat form the lattice microstructure. For example, FIGS. 10A-10Cillustrate various beam microstructures that can form the latticemicrostructure. FIG. 10A illustrates a cubic beam structure, while FIG.10B illustrates a hexagonal beam structure, and FIG. 10C illustrates anoctagonal beam structure. Other beam structures include tetragonal,rhombohedral, orthorhombic, monoclinic, and triclinic. FIGS. 11A-11Dillustrate that the beams can have various sizes. For example, FIGS.11A-11D illustrate beams having a diameter of about 100, 200 microns,350 microns, 500 microns, and 1000 microns. In other embodiments, thesize of the beam can vary between 50 microns to 5000 microns.

The matrix implant can be manufactured using a variety of techniques.For example, the matrix implant can be 3-D printed using a rapidprototyping technique involving additive manufacturing, such asdescribed in U.S. Patent Publication No. 2010/0161061, which is hereinincorporated by reference in its entirety for all purposes. The 3-Dprinted matrix implant can be made of a metal, polymer, or ceramicmaterial. For example, a metal powder such as titanium powder can befused together to form the implant structure. Other techniques includecutting out the fenestrations or openings, using a laser for example, toform the apex struts and support struts, or using electric dischargemachining (EDM) to create the matrixes or fenestrations.

3-D printing allows the porosity of the implant to be controlled. Forexample, the implant can have a volume porosity between about 30 and 70percent, with an average pore size between 100 and 1000 microns. Thepores can be largely interconnected, largely unconnected, or a mix ofinterconnected and unconnected pores. In some embodiments, the pores canbe located throughout the material of the implant, including the apexstruts and support struts, and on all or some of the strut surfaces,including the inner and outer implant surfaces. For example, the fusionof the beam microparticles to form the struts can result in a porous,semi-porous, or nonporous structure, depending on the degree of fusionbetween the beam microparticles. In other embodiments, the pores can belocated in a porous coating that can be applied onto the implant. Forexample, a porous coating can be applied using a titanium plasma sprayprocess, or another metal plasma spray process. The coating can beapplied to the outer surfaces of the implant, the interior surfaces ofthe implant, or both the outer and interior surfaces of the implant. Forexample, the coating could be preferentially applied to the outersurface of a matrixed implant to provide bony ingrowth and ongrowth, andnot applied to the inner portion of the implant to maximize bonythrough-growth within the implant. Also, the coating can be appliedpreferentially from proximal to distal, or vice versa. The thickness ofa porous coating can be between about 500 and 1,500 microns. In additionor alternatively to the porous metal coating, a hydroxyapatite coatingcan also be applied to the implant. In some embodiments, the porositycan be varied along the length of the implant. In some embodiments, thethickness of the coating can be varied along the length of the implant.In some embodiments, the thickness of the coating applied to the outersurface can be different than the thickness of the inner coating. Forexample, the outer coating may be greater than the inner coating in someembodiments. In other embodiments, the thickness of the inner and outercoatings can be the same.

In some embodiments, as illustrated in FIG. 12, the apex struts 14 canbe curved from the proximal end to the distal end of the apex strut 14,thereby resulting in a curved matrix implant 10 similar to the curvedimplants described in co-pending U.S. Provisional Application No.62/052,318, filed Sep. 18, 2014 and entitled “IMPLANTS FOR BONE FIXATIONOR FUSION,” which is herein incorporated by reference in its entiretyfor all purposes.

The length of the implant can vary between about 25 to 95 mm. The matrixstructure can be modular, as shown in FIG. 13, which allows the lengthof the implant to be varied by the addition of additional repeatingsubunits during the design and/or fabrication of the implant. Forexample, the modular matrix implant 130 can have a distal end portion132, a proximal end portion 134, and one or more repeating internalportions 136. The distal end portion 132 can have a distal guide pinreceptacle 138, and the proximal end portion 134 can have a proximalguide pin receptacle 136, much like the embodiments discussed above. Therepeating internal portion 136 can have apex struts 140 and supportstruts 142, as described above. For example, as shown, the supportstruts 142 can have an “X” configuration and can be located between twotransverse support struts 144. The two transverse support struts 144 canbe half the normal transverse support struts such that when tworepeating internal portions 136 are joined together, the two halfsupport struts merge to form a whole transverse support strut. Theproximal and distal end portions 132, 134 can also have a couplingportion that is formed from half transverse support struts 144 that canbe merged with the half transverse support struts 144 of the repeatinginternal portion 136. In some embodiments, the repeating internalportion 136 can also have an internal guide pin receptacle 146

In some embodiments, the length of the repeating internal portion 136can be about 10 mm. In other embodiments, the length can be betweenabout 5 and 25 mm. In some embodiments, the repeating internal portion136 can have support struts that form half an “X”, such that therepeating internal portions are arranged in an alternating pattern toform “X” shaped support struts. In some embodiments, the support strutsare simply diagonal struts that extend across the length of therepeating internal portion.

Methods of Implantation

The methods of implantation of the various implants described herein aredescribed in U.S. Patent Publication No. 2011/0087294, U.S. Pat. No.8,425,570, U.S. Pat. No. 8,444,693, U.S. Pat. No. 8,414,648, and U.S.Pat. No. 8,470,004, and co-pending U.S. Provisional Application No.61/891,326, each of which is herein incorporated by reference in itsentirety for all purposes. These methods are particularly suited for usewith straight implants.

The curved implant illustrated in FIG. 12 may require modifications tothe method of insertion protocols. Because the implant is curved, it maynot be possible or desirable to attempt to hammer or tap the implantinto the bone along a straight path using a straight guide pin, astraight drill, a straight broach and the like. Instead, it may bedesirable to create and form a curved insertion path that matches thecurvature of the implant.

For example, the tooling used to create the curved insertion path canhave a radius of curvature that matches the radius of curvature of theimplant. For example, some or all of the tooling and the implant canhave a matching radius of curvature. The tooling, which can include aguide pin, a tool guide, a drill bit, a broach, and impact hammer andthe like can be rotatably secured by an arm with a length equal to theradius of curvature, with one end of the arm attached to a pivot and theother end used to secure the tools and/or implant.

The rotating arm can be used to drive a curved guide pin into the boneto create a curved path through the bone, such as the ilium and thesacrum. A relatively short drill bit with a lumen for receiving theguide pin can be disposed over the curved guide pin to drill out acurved pilot bore. In some embodiments, the drill bit can be secured bythe pivoting aim at the end of a curved guide and can be used to drillthe curved pilot bore without the insertion of the curved guide pin.

For a curved implant with a circular cross section, the curved implantcan then be advanced over the curved guide pin and into the curvedinsertion path that is formed by the curved pilot bore. In someembodiments, the curved implant can be held by the pivoting arm andinserted into the curved insertion path without the aid of a guide pinby rotating the curved arm.

For a rectilinear implant or more broadly a noncircular implant, thecurved pilot bore can be shaped using an appropriately shaped broachthat matches the overall cross-sectional shape of the implant. A curvedbroach, or a short broach, can be advanced over the curved guide pin ifpresent, otherwise the curved broach or short broach can be held in thepivoting arm and advanced through the pilot bore by rotation of thepivoting arm. As the broach is advanced, it shapes the pilot bore into ashape that matches the shape of the implant.

The curved implant can then be advanced over the curved guide pin andinto the curved insertion path that is formed by the curved pilot bore.In some embodiments, the curved implant can be held by the pivoting armand inserted into the curved insertion path without the aid of a guidepin by rotating the curved arm.

More generally, the implants described herein can be used to fuse anytwo bone segments, such as two bones that form a joint or two bonesresulting from a fracture.

The terms “about” and “approximately” and the like can mean within 5,10, 15, 20, 25, or 30 percent.

It is understood that this disclosure, in many respects, is onlyillustrative of the numerous alternative device embodiments of thepresent invention. Changes may be made in the details, particularly inmatters of shape, size, material and arrangement of various devicecomponents without exceeding the scope of the various embodiments of theinvention. Those skilled in the art will appreciate that the exemplaryembodiments and descriptions thereof are merely illustrative of theinvention as a whole. While several principles of the invention are madeclear in the exemplary embodiments described above, those skilled in theart will appreciate that modifications of the structure, arrangement,proportions, elements, materials and methods of use, may be utilized inthe practice of the invention, and otherwise, which are particularlyadapted to specific environments and operative requirements withoutdeparting from the scope of the invention. In addition, while certainfeatures and elements have been described in connection with particularembodiments, those skilled in the art will appreciate that thosefeatures and elements can be combined with the other embodimentsdisclosed herein.

What is claimed is:
 1. A modular implant for the fixation or fusion ofthe SI-Joint, the modular implant comprising: a distal portioncomprising a distal guide pin receptacle; a proximal portion comprisinga proximal guide pin receptacle; and at least one repeating internalportion comprising: a plurality of apex struts joined together byoblique support struts arranged in an oblique configuration between theapex struts, and a plurality of transverse support struts arrangedperpendicularly to the apex struts, the plurality of transverse supportstruts arranged in a rectilinear configuration at both a proximal endand a distal end of the repeating internal portion; wherein the at leastone internal repeating portion is positioned between the distal portionand the proximal portion.
 2. The modular implant of claim 1, wherein theat least one repeating internal portion further comprises an internalguide pin receptacle secured to the oblique support struts and/ortransverse support struts and aligned with both the distal guide pinreceptacle and the proximal guide pin receptacle.
 3. The modular implantof claim 1, wherein the oblique supports struts are arranged in an “X”configuration.
 4. The modular implant of claim 1, wherein the obliquesupports struts are arranged in a non-overlapping diagonalconfiguration.
 5. The modular implant of claim 1, wherein the repeatinginternal portion has a rectilinear cross-sectional profile transverse toa longitudinal axis that extends from the proximal portion to the distalportion.
 6. The modular implant of claim 5, wherein the rectilinearcross-sectional profile is triangular.
 7. The modular implant of claim5, wherein the rectilinear cross-sectional profile is rectangular orsquare.
 8. An implant for the fixation or fusion of the SI-Joint, theimplant comprising: an elongate body having a longitudinal axis and arectilinear overall cross-sectional profile transverse to thelongitudinal axis, the elongate body having a proximal end and a distalend, the elongate body comprising: a plurality of apex struts alignedwith the longitudinal axis and extending between the proximal end andthe distal end of the elongate body; a plurality of support struts thatextend from one apex strut to another apex strut to form a matrixstructure; and a first guide pin receptacle located along thelongitudinal axis of the elongate body.
 9. The implant of claim 8,wherein the rectilinear overall cross-sectional profile is triangular.10. The implant of claim 8, wherein the rectilinear overallcross-sectional profile is rectangular or square.
 11. The implant ofclaim 8, wherein the elongate body is curved along the longitudinal axisfrom the proximal end to the distal end of the elongate body.
 12. Theimplant of claim 11, wherein the elongate body has a curvature betweenabout 5 and 45 degrees.
 13. The implant of claim 8, wherein the elongatebody has a curvature between about 15 and 30 degrees.
 14. The implant ofclaim 8, wherein the guide pin receptacle has a circular opening adaptedto securely receive a guide pin.
 15. The implant of claim 8, wherein theelongate body is coated with a titanium plasma spray.
 16. The implant ofclaim 8, wherein the elongate body is coated with hydroxyapatite. 17.The implant of claim 8, wherein the elongate body is made of metal. 18.The implant of claim 17, wherein the metal is titanium.
 19. The implantof clam 17, wherein the metal comprises a lattice structure.
 20. Theimplant of claim 19, wherein the lattice structure is cubic.
 21. Theimplant of claim 20, wherein the lattice structure is hexagonal.
 22. Theimplant of claim 19, wherein the lattice structure comprises a pluralityof beams with a diameter between about 100 to 1000 microns.
 23. Theimplant of claim 8, wherein the elongate body is made of a ceramicmaterial.
 24. The implant of claim 8, wherein the elongate body is modeof a plastic material.
 25. The implant of claim 8, wherein the elongatebody has a porous outer surface.
 26. The implant of claim 25, whereinthe porous outer surface has a pore size between about 100 to 1000microns.
 27. The implant of claim 8, wherein the thickness of the apexstruts and the support struts is between about 1 to 5 mm.
 28. Theimplant of claim 8, wherein the first guide pin receptacle is located atthe distal end of the elongate body.
 29. The implant of claim 8, whereinthe first guide pin receptacle is located at the proximal end of theelongate body.
 30. The implant of claim 8, wherein the first guide pinreceptacle is located at the distal end of the elongate body and asecond guide pin receptacle is located at the proximal end of the body.31. The implant of claim 30, further comprising a cannula extendingbetween the first guide pin receptacle and the second guide pinreceptacle.
 32. The implant of claim 30, wherein a third guide pinreceptacle is located between the first guide pin receptacle and thesecond guide pin receptacle.
 33. The implant of claim 30, wherein aplurality of pin receptacles are located between the first guide pinreceptacle and the second guide pin receptacle.